import json
a='{"singleResult":"{\\"errorInfo\\":\\"\\\\u627e\\\\u4e0d\\\\u5230\\\\u67e5\\\\u8be2\\\\u8bb0\\\\u5f55\\",\\"0\\":{\\"startTime\\":\\"2018-03-31 17:09:24\\",\\"endTime\\":\\"2018-03-31 17:09:24\\",\\"useTime\\":\\"231ms\\"}}","code":3}'

j=json.loads(a);
print(json.dumps(j,ensure_ascii=False))
s=j['singleResult']



print(json.dumps(json.loads(s),ensure_ascii=False) )